1. Field of the Invention
The present invention relates to a torque generating device which uses shape memory alloy to continuously convert heat energy to mechanical energy.
2. Prior Art Statement
Because geothermal water, heated waste water discharged by factories and other such low-grade heat energy cannot be readily converted into rotational or other such mechanical energy, in virtually all cases such energy is therefore discarded. There is thus a need for a way of effectively utilizing such energy.
In U.S. Pat. Application Ser. No. 433,137, now U.S. Pat. No. 5,031,711, the present inventor proposed a conveyance device which is operated by converting heat energy to mechanical rotational energy. In the conveyance device, a chassis supports a pair of pulleys separated by a prescribed distance, and an endless belt made of shape memory alloy runs between the pulleys One of the pulleys is maintained at a temperature which is higher than the transformation temperature of the shape memory alloy and the other pulley is maintained at a temperature that is lower than the transformation temperature. The shape memory alloy is provided with a curve which curves in the opposite direction to the belt's curvature around the pulleys, whereby as a result of the transformation force and reversion force the pulleys are turned by the belt and move the chassis Using a shape memory alloy with a low transformation point temperature would enables the device to be driven by low temperature heat energy, but because the shape memory alloy moves, being mounted on the chassis, it is difficult to use low grade heat energy as the source for heating the shape memory alloy.
The object of the present invention is therefore to provide a torque generating device which is able to continuously generate relatively large rotational energy by the conversion of low grade heat energy of 100.degree. C. or less.